The present invention concerns an adaptive headset interface for connection between any host terminal and a so-called headset as defined in claim 1, and methods for the calibration of the headset interface as defined in claims 10 and 11.
Headsets are used as an alternative to the conventional hand-held telephones or handsets which comprise a microphone and a loudspeaker, by users who typically use the telephone for many hours during the course of the day, and by users who because of their work situation have their hands occupied with something else and are therefore engaged, or by users who find that headsets are more comfortable.
It is desirable to be able to connect a headset to different types of host terminals. However, these different types of host terminals have varying sensitivity and amplification, the reason being that the host terminal is adapted in accordance with individual microphone and loudspeaker specifications.
In document WO/95/26604 there is described an adaptive headset which can generate adjusted signal levels between the host terminal""s normal connection to its microphone/ loudspeaker and the connection to the headset. This adaptive interface contains a processor which generates a series of test signals with varying values of amplitude which are sent to the host terminal. The generated signals are monitored by the processor by means of the host telephone""s sidetone coupling, in that the processor analyses the sidetone and determines when a clipping of the transmitted test signal occurs. The amplitude of the microphone signal is adjusted automatically to an output level which is sufficiently high and herewith free of noise, but without any overdriving of the host telephone""s microphone input circuit.
This document forms the basis for the introductory part of claim 1.
The object of the present invention is to provide methods for the mode of operation of a headset interface, and an apparatus herefor which is able to offer an improved adaptation between the headset and the terminal while taking into account a coupled reference telephone line which is representative of a country-specific standard, and which is further able to adjust any headset to suit any host terminal complying with a country-specific standard for telephone apparatus. It is also an object of the invention to provide an apparatus with a set-up and calibration which requires a minimum of operation.
These objects are achieved with an apparatus as defined in claim 1 and by the methods according to the claims 9 and 10.
It is a further object to provide a headset interface which, despite its complex mode of operation, is simple to produce. This object is achieved through claim 2.
It is a further object of the present invention to provide a headset interface having a set-up and calibration which is independent of the type or the standard for the connectors of the host terminal which is used. This object is achieved through claims 3 and 11.